Pole piece assembly



June 29, 1943. Z Q B ADFORD HAL 2,323,114

POLE PIECE ASSEMBLY Filed Feb. 26, 1942 fNl/ENTURE 2525:": c. BRADFORD AND CALVIN J. WERNER EDWARD 8.5LEE'TER .AT THRIVE Y5 Patented June 2 9, 1943 B. Sleeter, Dayton, Ohio, ass'ignors to General v Motors Corporation, Detroit, Mich., a corporation of Delaware Application February 2c, 1942, seria N0..432,402 I Clainis. uip-252) This invention relates to improvements in laminated core constructions for electrical de vices and particularly to laminated pole pieces for dynamo electric machines.

It is among the objects of the present invention to provide a simple and easily assembled laminated core construction forming polepieces for a dynamo electric machine.

A further object of the present invention is to provide a core. assembly forming pole pieces for a dynamo electric machine which may easily be placed and secured within a housing member without affecting the proper spacing of the several pole pieces relatively to each other.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawing wherein a preferred embodi ment of the present invention is clearly shown.

In the drawing:

Fig. 1 illustrates one of the pole piece laminae.

Fig. 2 is a view of the assembled core.

Fig. 3 shows the laminated core assembled in the housing of the electrical device, in this instance the cylindrical frame of a dynamoelectric machine.

Referring to the drawing the numeral 20 designates, as a whole, the improved core assembly for a dynamo-electric machine. This core comprises spaced pole pieces or shoes 2|, 22, 23 and 24 each consisting of a stack of magnetic metal elements 25 of a predetermined size and shape as shown in Fig. 1. Certain of the metal elements of each stack or pole piece are part of an integral member comprising a web 26 connecting the portion of one element adjacent the corresponding portion of the other. In the present drawing the two outer metal elements of each stack forming pole pieces 2|, 22, 23 and 24 are an integral unit respectively including the portions 25 as shown in Fig. l, and the connecting, circularly shaped web portion 26. The inner edge contour of the portions 26 and 26 form a circle through which the armature of the electric machine, not shown, is adapted to extend. Other metal laminae of the assembly are also integral units which are spaced apart at intervals between the two ends of the assembly. Thus, as shown in the present drawing four metal laminae of each stack forming a pole piece, are separate integral units including corresponding laminae of the other stacks and connecting, ring-shaped web portions, two of these integral units being the two outer laminae of the assembly the other two being spaced equidistant from each other and from the said end units. These unitary laminae of the four pole pieces may be of the same comparatively soft iron'as the parts 25. Preferably, howeven'these unitary laminaeare made from a stiffer and harder material so that they may more readily maintain their rigidity and thus resist deformation during the assembling operation. They may be non-magnetic.

To maintain thelaminae oi the core in assem bled relationship rivets 28 extend through holes pasing longitudinally through each of the sev-= eral stacks of laminae forming the pole shoes or pieces. These rivets tightly clamp the assembly together and prevent relative movements of the laminae when the core is assembled in the housing of the electric device.

The core assembly 20, illustrated as one form of the present invention, is adapted to be secured in a cylindrical motor housing 30. In this instance the inner diameter of the motor housing 30 is smaller than the outer diameter of the core assembly 20.

To complete the core assembly before its introduction into the cylindrically shaped housing the field windings of the electric device are placed about the several pole shoes or pieces.

When assembling the core 20 and motor housing 30, the housing may be heated so as to expand it and permit the introduction of the core assembly 20 which, as has been stated is of greater diameter than the normal inside diameter of the housing 30. While the housing 30 is cooling, the core assembly is maintained in proper position in the housing. When completely cooled, the housing will have again shrunk to its normal size thereby securely embracing and holding the core assembly within it. If desired the entire housing assembly may be coated with a protective or insulating coating to be hardened either by air drying or baking under heat.

Thistype of construction entirely eliminates the use of screws or bolts for fastening the pole pieces or shoes within the housing as is the usual practice, thereby avoiding openings or apertures in said housing through which such screws or bolts extend. Thus, in an electric motor to be used in the presence of an explosive atmosphere or gas, which necessitates sealing of the motor to prevent the entrance of such an atmosphere or gas, apertures or openings providing for leakage are substantially reduced and consequently the necessity of sealing such openings or apertures is likewise avoided.

From the aforegoing it may be seen that applicant has provided an improved core assembly for an electric device, particularly for dynamoelectric machines, which is of simple structure and design, inexpensive and which may be commercially produced at a, minimum expense of time and labor.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. An electrical device core comprising stacks of laminae of magnetic material forming pole pieces, certain laminae of a stack being integral with corresponding laminae in the same plane of the other stacks whereby said stacks are properly spaced; and rivets passing longitudinally through each stack of laminae to hold them in assembled relationship.

2. An electrical device core comprising a plurality of stacks'of formed pieces of magnetic material; interconnecting web portions integral with each end piece and certain corresponding pieces of all of the stacks whereby the several stacks are properly spaced; and rivets passing longitudinally through each stack of laminae, clamping them in assembled relationship.

3. An electrical device core comprising stacks of laminae of magnetic material forming pole pieces, certain laminae at spaced intervals in each stack being of a harder and stiffer metal than the other laminae in the stacks, each hard metal lamina of a stack in the same plane as the corresponding laminae of the other stacks being integral one with the other whereby each stack of laminae is properly spaced relatively to its adjacent stack; and rivets passing longitudinally through each stack of laminae for holding them rigidly in assembled relationship.

4. An electrical device core comprising a plurality of compact stacks of laminae of magnetic material forming pole pieces, certain laminae of each stack having integral extending web portions which are integral with similar web portions of laminae of adjacent stacks and in the same plane whereby the several stacks are held in proper relative positions; and means in each stack of laminae for holding it in assembled relationship.

5. An electrical device core comprising stacks of laminae of magnetic material forming pole pieces certain laminae of a stack being integrally bound with corresponding laminae in the same plane and of all of the other stacks by a circularly shaped web portion forming ring shaped laminae holding the several stacks of laminae in proper spaced relation; and means arranged longitudinally of each stack of laminae for holding them in assembled relationship.

ZERBE C. BRADFORD. CALVIN J. WERNER.

EDWARD B. SLEETER. 

